Electrically controlled sewing machines



A ril 6,1965

Filed Oct. 3. 1962 4 Sheets-Sheet 1 April 6, 1965 G. w. PALMERELECTRICALLY CONTROLLED SEWING MACHINES 4 sheets-sneak; 2

Filed Oct. 3, 1962 Fparye MI/zamPalmar April 6, 1965 e. w. PALMER3,176,641

7 ELECTRICALLY CONTROLLED SEWING MACHINES Filed Oct. 5, 1962 4Sheets-Sheet a m wf e eoryeWEf/zazzzfialmer A ril 6, 1965 G. w. PALMERELECTRICALLY CONTROLLED SEWING MACHINES 4 Sheets-Sheet 4 Filed Oct. 3,1962 61 02" a WEI/1am Palmar In. 7

United States Patent 3,176,641 ELECTRHCALLY CONTROLLED SEWlNG MACSGeorge William Palmer, Leyton, London, England, msignor to Lights LondonLimited Filed Oct. 3, 1962, Ser. No. 228,123

Claims priority, application Great Britain, Oct. 19, 1961,

37,572/61 7 Claims. (Cl. 112219) This invention relates to electricallydriven sewing machines. In the operation of such sewing machines it iscustomary to stop the sewing needle of the machine simply by declutchingthe drive from the motor to the sewing needle. Upon declutching, theinertia of the moving parts of the needle drive causes the needle tooscillate vertically and come to rest in a position which may beanywhere in the range of movement of the needle. If the machineoperator, for example, desires to remove a workpiece from the machineand declutches the drive to the needle for this purpose it may wellhappen that the needle sops whilst it is in engagement with theworkpiece. This in turn means that the needle has to be brought manuallyinto a position outside the workpiece before removal of the workpiececan take place.

According to the present invention, an electrically driven sewingmachine comprises an electric motor having a first shaft, driving wheelmeans freely rotatably mounted on the first shaft, a sewing needle driveincluding a second shaft, driven wheel means mounted on the second shaftfor co-operation by means of an endless band with the driving wheelmeans, electromagnetic clutch means including a driving member mountedon the first shaft for rotation therewith and a driven member mountedfor rotation with the driving wheel means, elec-- tromagnetic brakemeans including a first element mounted on the second shaft for rotationtherewith and a second element for attracting and thereby arresting thefirst element upon energization of the brake means, cam means providedon the second shaft and adapted during rotation thereof to actuatecontact means electrically connected with the brake means and switchingmeans adapted to switch a source of electrical power from the clutch tothe brake means thereby to-elfect energization of the brake means uponactuation of the contact means and consequent arresting of the secondshaft.

It will be apparent that with a sewing machine according to theinvention upon switching of electric power to the brake meansenergization of the brake means does not take place until the cam meanshave actuated the contact means. In the interval between de-energizationof the clutch and energization of the brake means the needle of3,176,641 Patented Apr. 6, 1965 FIGURE 4 is a front elevation of anupper part of the machine of FIGURES lto 3, the casing of the machinebeing partly broken away to illustrate details of the interior thereof;7

FIGURE shows a detail of the machine; and

FIGURE 6 shows in diagrammatic form an electrical circuit of themachine. 7

Referring to the drawings, an electrically'driven sewing machine,generally designated 1, is provided with an induction motor 2 the shaft3 of which, otherwise herein called the first shaft, is arrangedhorizontally below a table 4 of the machine to extend in a directionfrom front to rear of the table. A head casting 5 of the sewing machinewhich is mounted on the upper side of the table 4 also extends fromfront to rear of the table so that a needle drive shaft 6, otherwisereferred to herein as the second shaft, in the machine head is disposedparallel with the first or motor shaft. The drive from the second shaft6 to the needle for vertical reciprocation of the latter is largely ofconventional known form and includes a collar 7 in which a vertical post8 which at its lower end carries a needle 9 is mounted for verticalreciprocation by means of a link 10 and eccentric 11 of known form, the

the sewing machine reciprocates due to the inertia of the FIGURE 1 is aside elevation of an electrically driven sewing machine according to theinvention;

FIGURE 2 is a fragmentary side elevation, partly in section of themachine of FIGURE 1 drawn to a larger scale than that figure;

FIGURE 3 is a sectional side elevation drawn to a larger scale thanFIGURE 1 of a rear part of the machine;

It follows, therefore, that the needle can be eccentric 11 being keyedto the forward end of the shaft 6. A presser foot 12 is arranged formovement parallel with the direction of movement of the sewing needle 9.To this end the foot 12 is carried on a vertical rod 13 which isslidable in collars 14 and 15. On the rod 13 is secured a member 16which has a laterally projecting abutment piece 17, the latterco-operating with a cam portion 18 of a lever 19 Which is pivoted at 20for movement in a vertical plane. It will be seen that on upward andoutward rotation of lever 19the cam portion 18 co-operates with theabutment piece 17 to effect lifting of the foot 12.

Above the member 16 there is fixed on the rod 13 a member 21 thefunction of which is hereinafter described. Between member 21 and collar15 a helical spring 22 is provided which biasses the rod 13 downwardly.Thus, upon release of lever 19 from its uppermost position, the spring22 effects downward movement of the presser foot.

A driving wheel 25 (see FIGURE 3) in the form of a pulley is freelyrotatably mounted on the first shaft by means of a ball race 26 andco-operates by means of an endless belt 27 with a driven pulley 28 keyedto the second shaft 6 and forming part of a fly wheel 29. On the rearface of the driving wheel remote from the motor is secured as by screws36 to rotate with the pulley a plate 31 of an electromagnetic clutch 32.The plate 31 is formed with a rearwardly projecting central boss 33 theouter surface of which is formed with splines 34 extendinglongitudinally of the motor shaft 3. Complementarily engaged on thesplines of the boss 33 is a driven plate member 35 of the clutchprovided on its rear face with a suitable friction lining. The platemember 35 can thus move axially relative to the wheel 25 but isretatable with that wheel. Opposed and adjacent to the driven platemember 35, the clutch includes a driving plate member 36 which issecured to the first shaft 3 as by screw 37 and which has a suitablefriction lining on its forward face. On the side of the driving platemeniber 36 remote from the driven plate member 35 is an energizingclutch coil 38 which is disposed in a housing 39 arranged concentricallywith the first shaft 2 and carried on a bracketed secured to the casingof the motor 2.

The housing 39 includes inner and outer cylindrical walls 42 and 43concentric with shaft 2 and closed at rear ends thereof by radial wall44 which is secured to a plate 45 in turn secured to bracket 49. At theforward ends of the walls 42 and 43, the periphery of the driving plate7 the wall 43 whilst a rearwardly projecting annular wall 46 of themember 36 closely overlies the forwardend of inner wall 42. Thus theannular gap between the walls 42 and 43 is substantially closed bydriving plate men her 36. On rotation of shaft 2 the member 36 rotatestherewith and when coil 38 is energized driven plate member 35 ismagnetically attracted to member 36 and moves into contact therewithalong the splines 34. In this way the driving wheel 25 is caused torotate with the motor shaft 3. V 7

On the second shaft 6 near the driven pulley 28 is mounted a brake platewhich is keyed to the driven pulley so as to be capable of limited axialmovement relative thereto. To this end on the rear face of pulley 28 issecured a boss 51 formed on its outer surface with axially extendingsplines with which the brake plate 5 co-operates. On the side of thebrake plate 5% remote from the driven pulley is provided an annularbrake housing 52 disposed concentrically with the second shaft 6 andsecured to a plate 53 in turn secured to a bracket 54 carried on thehead casting 5. Within the brake housing 52 is provided a brakeenergizing coil 55 which, when energized, magnetises a front plate 56 ofthe housing adjacent the brake plate 5% causing the latter to beattracted to the housing and thereby stopping the second shaft. Theforward and rear surfaces of the housing front plate 56 and brake plate50 respectively are suitably friction lined.

On an end of the second shaft 6 projecting rearwardly of bracket 54 isprovided a cam 60 which is secured to the shaft for rotation therewith.Engaging the cam and mounted on the rear face ofthe bracket 54 is a camfollower 61 which is pivoted at 62 .andbiassed by spring 63 (see FIGURE5) towards the cam. The follower carries one contact 64 of a pair ofcontacts, the other contact 65 of the pair being mounted on an insulatedsupport 66 carried on the rear face of the bracket54. The action ofthe'cam follower biassing spring is to bias towards closure the pair ofcontacts whilst urging the follower into contact with the cam androtation of the cam causes the follower to be-rnoved, once perrevolution,

under the action of the biassing spring to efiect closure of a thecontacts. As shown in'FIGURE 5 the cam 6tlhas a flat 67 and When theflat is engaged by the follower 1 the contacts 64- and 65 are closed. 7

Referring now to FIGURE 6, a field winding 79 of the induction motor 2is supplied from an alternating current supply 71 by way of a doublepole mains switch 72.

Suitably, the alternating current supply is a 250 volts S0 1 V movementof a contact arm 76 of the microswitch 74 upon raising or lowering ofthe presser foot 12. When the presserfoot is raised the arm 76 isbiassed into engagement with afirst contact 77 of the microswitch andwhen the presser foot is lowered the element 75 moves the arm 76 intocontact with a second contact 78 of the microswitch whereupon the outputof the rectifier energizes the clutch coil 38.

Connected between the contact 77 and the output side of the rectifier 73opposite that to which the contact arm 76 is connected are parallelbranches respectively including a lamp 84 mounted on the side of thehead of the machine and the brake coil in series with the cam actuatedcontacts 64 and 65. It will be apparent that when the contact arm 76engages contact 77 in the raised position of the presser foot, the lamp8% and coil 55 and contacts 64 and 65 are connected across the rectifier73 so that when the cam causes contacts 64- and to close, the brake isenergized and effects stopping of the needle 9, the cam 6% beingappropriately shaped to cause the contacts 64 and 65 to close when theneedle is in its uppermost position.

It will be noted that the presser foot does not have to be fully raisedto eiiect actuation of the microswitch 74. Because of this, and ashereinafter described, the machine is particularly suited for use withthe device described in co-pending application No. 170,622.

For a variety of reasons, for example, stiffening of bearings, excessivewear on parts or inadequate lubrication, it may infrequently happen thatupon energization of the brake coil, the needle stops'in some positionother than that predetermined by the shape of the cam 60. In thiseventuality, it is desirable that the operator of the machine should beable to bring the needle to its uppermost position without havingmanually to rotate pulley 28. To this end there is connected betweencontacts 77 and 78 of microswitch 74 a branch circuit comprising avariable resistor 81 in series with contacts 82 and 83 of a microswitch84 disposed on the side of the machine and adjacent microswitch 74. Thecontacts 82 .and 83am actuated to close by movement of the element bythe lever 19 to a position slightly above that at which the element 75permits the contact arm of the microswitch 74 to engage contact 77. Ifthe lever 19 is moved so that the element 75 passes the position atwhich the contacts 82 and 33 close, these contacts immediately re-open.In use the lever 19 is moved so that the element 75 momentarily closesthe contacts of microswitch 84 and when this happens the clutch coil 38is energized in series with resistor 81 and drives the machine until thecam 60 once again closes contacts 64 and 65 to energize the brake coiland bring the machine needle to its uppermost position. The resistor 81is adjusted so that if the clutch'coil is still energized when contacts64 and 65 close, the clutch will slip as a result of the load imposed onthe needle drive by the brake. It will be noted that the resistor 81 ismounted on the side of the head of the machine.

In operation of the machine, the foot is raised to its uppermostposition by lever 19 and the switch 72 is closed- A workpiece is theninserted below the presser foot and the foot is lowered whereuponcontact arm 76 closes with contact 78 and the clutch coil 38 isenergized to initiate sewing. When it is required to stop sewing thelever 19 is moved to raise the presser foot 12 and at the same timeeffect closure of contact arm 76 with contact 77. At this instant theclutch is de-energized and the rive to the needlecontinues to move underits own inertia until the cam 60 reaches the position at which it closescontacts 64 and 65 and thereby energizes the brake coil 55 to stop theneedle drive with the needle in its uppermost position.

As mentioned above the invention is particularly suitable for use withthe device described in co-pending application No. 170,622. When usedwith this device the presser foot of the machine is provided with adownwardly extending projection which engages with the sewing track ofthe device.

Initially, the presser foot is lowered on to the top of the device sothat the projection on the lower side of the presser foot contacts thetop sheet of the device. The clutch winding is not, however, energizeduntil the projection on the presser foot is lowered into the sewingtrack of the device. 7 When the projection on the presser foot is solowered, the machine commences sewing. At the end of the track thepresser foot is automatically raised on the ramps provided at the end ofthe track and the raising of the presser foot effects automatic stoppingof the machine with the needle in its predetermined position, suitablyits uppermost position. If the needle does not stop in its predeterminedposition, it is brought to this position by movement of lever 19 toeffect momentary actuation of microswitch 84. s

I claim: 1. In a sewing machine having a needle mounted for movement upand down along a defined path and an electric motor for driving theneedle in such up and down 7 motion:

(A) a driving shaft rotatable with the electric motor;

(B) a driving wheel mounted for rotation relative to the driving shaft;

(C) electromagnetic clutch means operatively associated with the drivingshaft and the driving wheel and comprising (1) a coupling elementmovable between a clutch engaged position at which the coupling elementconstrains the driving wheel to rotate with the driving shaft and aclutch disengaged position at which the coupling element permits thedriving wheel to rotate relative to the driving shaft, and

(2) first electromagnet means energizable to hold the coupling elementin one of its said positions;

(D) needle actuating means comprising (1) a rotatable driven shaft and(2) means for translating rotation of the driven shaft into up and downmotion of the needle;

(E) a driven wheel constrained to rotation with the driven shaft;

(F) means providing a rotation transmitting connection between thedriving wheel and the driven wheel through which the motor can drive theneedle in up and down motion when the coupling element of theelectromagnetic clutch means is in its first designated position;

(G) electromagnetic brake means operatively associated with the drivenwheel and comprising (1) a brake element movable between a brakedisengaged position and a braking position, at the latter of which saidbrake element is engaged with the driven wheel and with a fixed part onthe sewing machine to restrain the driven wheel against rotation, and

(2) second electromagnet means energizable to move said brake elementfrom one to the othe of its said positions;

(H) means for controlling energization of said first and secondelectromagnet means from a current source to effect movement of thebrake element to its braking position concomitantly with movement of thecoupling element to its clutch disengaged position, and for effectingmovement of the coupling element to its clutch engaging positionconcomitantly with movement of the brake element to its brake disengagedposition, said last named means comprising (1) switch means,

(2) conductor means connected with said switch means and with the firstand second electromagnet means and connectable with a current source,and

(3) manually operable actuator means for said switch means; and t (I)cam means constrained to rotation with the driven wheel and operativelyassociated with the electromagnetic brake means for causing the brakeelement to engage the driven wheel when the latter is in a predeterminedposition of rotation corresponding to a desired position of the needlealong its path of motion.

2. The sewing machine of claim 1, further characterized by the fact thatsaid manually operable actuator means for the switch means also servesas an actuator for a presser foot that is movable downwardly to andupwardly from an operative position.

3. The sewing machine of claim 1 wherein the coupling element is movableto its clutch engaged position in consequence of energization of thefirst electromagnet means and the brake element is movable to itsbraking position in consequence of energization of the secondelectromagnet means, further characterized by the fact that: said switchmeans comprises a double-throw switch having a movable contactorconnectable with a current source, and having a pair of terminals thatare alternatively connectable with said contactor, depending upon theposition of the latter, and which are respectively connected with thefirst and second electromagnet means, so that said switch efiectsenergization of one of said electromagnet means concomitantly withde-energ'ization of the other.

4. The sewing machine of claim 3, further characterized by thefollowing:

(A) said switch means also comprises a single-pole single-throw switchconnected between the second electromagnet means and that terminal ofthe doublethrow switch with which the second electromagnet means isconnected, so that the second electromagnet means cannot be energizedunless the single-throw switch is closed; and

(B) the cam means comprises an actuator for said single-polesingle-throw switch whereby the latter is closed only when the drivenwheel is in its said predetermined rotational position.

5. The sewing machine of claim 1 wherein the coupling element is movableto its clutch engaged position in consequence of energization of thefirst electromagnet means and the brake element is movable to itsbraking position in consequence of energization of the secondelectromagnet means, further characterized by the following:

(A) said switch means comprises a double-throw switch having a movablecontactor connectable with a current source and having a pair ofterminals that are alternatively engageable by said contactor, dependingupon the position of the latter,

(1) one of said terminals being connected with the first electromagnetmeans, and

(2) the other of said terminals being connected with the secondelectromagnet means;

(B) another switch is connected in series between the second mentionedterminal of the double-throw switch and the first electromagnet means,said other switch being normally open and being manually actuatable toits closed position to cause the coupling element to move to its clutchengaged position in the event the driven Wheel stops in a position otherthan said predetermined position of rotation; and

(C) impedance means connected in series circuit with said other switchand the first electromagnet means so that the first electromagnet meansexerts a less than normal clutching force with said other switch closed,permitting continued rotation of the driving wheel after the drivenwheel is restrained by the braking element.

6. The sewing machine of claim 5, further characterized by the factthat: said impedance means comprises a variable resistor connectedbetween the second mentioned terminal of the double-throw switch andsaid other switch.

7. The sewing machine of claim 5, further characterized by (A) apresserfoot movable up and down between a lowered operative position anda raised inoperative position;

(B) a manual actuator for the presser foot connected 7 V with the latterand movable in opposite directions to predetermined positions, motion ofsaid actuator in one direction to one of its positions etfectinglowering of the presser'foot to its operative position, motion of theactuator in its opposite direction to another of its positions effectingraising of the presser foot to its inoperative position, and saidactuator being. movable further in its said other direction to a specialbraking position; 7

8 (D) means mechanically connecting the manual actu- References Cited bythe Examiner ator with the double-throw switch means whereby 1 UNITEDSTATES PATENTS movement of the actuator-to its first mentioned positionengages the contactor of the double-throw switch 2, 7 10/ 54 Bliedung eta1. 112219 with the first mentioned terminal and movement of 5 2,876,4073/59 Winz 112-219 the actuator to its second mentioned position engages2,942,564 6/60 Larys et a1 112-219 the actuator with said otherterminal; and 2,962,992 12/60 Johnson et a1. 112-219 (E) meansmechanically connecting said actuator with said other switch meanswhereby the latter is JORDAN FRANKLIN, Primary Examiner.

closed in'consequence of movement of the actuator 10 to its Specialbraking Position DAVID J. WILLIAMOWSKY, Exammer.

1. IN A SEWING MACHINE HAVING A NEEDLE MOUNTED FOR MOVEMENT UP AND DOWNALONG A DEFINED PATH AND AN ELECTRIC MOTOR FOR DRIVING THE NEEDLE INSUCH UP AND DOWN MOTION: (A) A DRIVING SHAFT ROTATABLE WITH THE ELECTRICMOTOR; (B) A DRIVING WHEEL MOUNTED FOR ROTATION RELATIVE TO THE DRIVINGSHAFT; (C) ELECTROMAGNETIC CLUTCH MEANS OPERATIVELY ASSOCIATED WITH THEDRIVING SHAFT AND THE DRIVING WHEEL AND COMPRISING (1) A COUPLINGELEMENT MOVABLE BETWEEN A CLUTCH ENGAGED POSITION AT WHICH THE COUPLINGELEMENT CONSTRAINS THE DRIVING WHEEL TO ROTATE WITH THE DRIVING SHAFTAND A CLUTCH DISENGAGED POSITION AT WHICH THE COUPLING ELEMENT PERMITSTHE DRIVING WHEEL TO ROTATE RELATIVE TO THE DRIVING SHAFT, AND (2) FIRSTELECTROMAGNET MEANS ENERGIZABLE TO HOLD THE COUPLING ELEMENT IN ONE OFITS SAID POSITIONS; (D) NEEDLE ACTUATING MEANS COMPRISNG (1) A ROTATABLEDRIVEN SHAFT AND (2) MEANS FOR TRANSLATING ROTATION OF THE DRIVEN SHAFTINTO UP AND DOWN MOTION OF THE NEEDLE; (E) A DRIVEN WHEEL CONSTRAINED TOROTATION WITH THE DRIVEN SHAFT; (F) MEANS PROVIDING A ROTATIONTRANSMITTING CONNECTION BETWEEN THE DRIVING WHEEL AND THE DRIVEN WHEELTHROUGH WHICH THE MOTOR CAN DRIVE THE NEEDLE IN UP AND DOWN MOTION WHENTHE COUPLING ELEMENT OF THE ELECTROMAGNETIC CLUTCH MEANS IS IN ITS FIRSTDESIGNATED POSITION; (G) ELECTROMAGNETIC BRAKE MEANS OPERATIVELYASSOCIATED WITH THE DRIVEN WHEEL AND COMPRISING (1) A BRAKE ELEMENTMOVABLE BETWEEN A BRAKE DISENGAGED POSITION AND A BRAKING POSITION, ATTHE LATTER OF WHICH SAID BRAKE ELEMENT IS ENGAGED WITH THE DRIVEN WHEELAND WITH A FIXED PART ON THE SEWING MACHINE TO RESTRAIN THE DRIVEN WHEELAGAINST ROTATION, AND (2) SECOND ELECTROMAGNET MEANS ENERGIZABLE TO MOVESAID BRAKE ELEMENT FROM ONE TO THE OTHER OF ITS SAID POSITIONS; (H)MEANS FOR CONTROLLING ENERGIZATION OF SAID FIRST AND SECOND ELETROMAGNETMEANS FROM A CURRENT SOURCE TO EFFECT MOVEMENT OF THE BRAKE ELEMENT TOITS BRAKING POSITION CONCOMITANTLY WITH MOVEMENT OF THE COUPLING ELEMENTTO ITS CLUTCH DISENGAGED POSITION, AND FOR EFFECTING MOVEMENT OF THECOUPLING ELEMENT TO ITS CLUTCH ENGAGING POSITION CONCOMITANTLY WITHMOVEMENT OF THE BRAKE ELEMENT TO ITS BRAKE DISENGAGED POSITION, SAIDLAST NAMED MEANS COMPRISING (1) SWITCH MEANS, (2) CONDUCTOR MEANSCONNECTED WITH SAID SWITCH MEANS AND WITH THE FIRST AND SECONDELECTROMAGNET MEANS AND CONNECTABLE WITH A CURRENT SOURCE, AND (3)MANUALLY OPERABLE ACTUATOR MEANS FOR SAID SWITCH MEANS; AND (1) CAMMEANS CONSTRAINED TO ROTATION WITH THE DRIVEN WHEEL AND OPERATIVELYASSOCIATED WITH THE ELECTROMAGNETIC BRAKE MEANS FOR CAUSING THE BRAKEELEMENT TO ENGAGE THE DRIVEN WHEEL WHEN THE LATTER IS IN A PREDETERMINEDPOSITION OF ROTATION CORRESPONDING TO A DESIRED POSITION OF THE NEEDLEALONG ITS PATH OF MOTION.